AS3 - 仅触发一次的事件侦听器 [英] AS3 - Event listener that only fires once

问题描述

我正在寻找一种方法来添加一个EventListener，它会在第一次触发后自动删除它，但是我无法想像这样做。

I'm looking for a way to add an EventListener which will automatically removes itself after the first time it fires, but I can't figure a way of doing this the way I want to.

我发现这个功能（ here ）：

public class EventUtil
{
    public static function addOnceEventListener(dispatcher:IEventDispatcher,eventType:String,listener:Function):void
    {
         var f:Function = function(e:Event):void
         {
              dispatcher.removeEventListener(eventType,f);
              listener(e);
          }
          dispatcher.addEventListener(eventType,f);
    }
}

但不必写： / p>

But instead of having to write :

EventUtil.addOnceEventListener( dispatcher, eventType, listener );

我想以通常的方式使用它：

I would like to use it the usual way :

dispatcher.addOnceEventListener( eventType, listener );

有人知道如何做到这一点吗？

任何帮助将被大大的欣赏。

---

（我知道Robert Penner的信号可以这样做，但是我不能使用它们，因为这意味着很多代码重写，我现在的项目无法承受）

Has anybody got an idea of how this could be done?
Any help would be greatly apprecitated.

---

(I know that Robert Penner's Signals can do this, but I can't use them since it would mean a lot of code rewriting that I can't afford for my current project)

推荐答案

我发现最简洁的方式，而不使用静态或者弄乱你的代码是为了定义一个全局函数（在一个名为removeListenerWhenFired.as的文件中），如下所示： / p>

I find the cleanest way without using statics or messing up your code with noise is to defining a global function (in a file called removeListenerWhenFired.as) like so:

package your.package
{
    import flash.events.Event;
    import flash.events.IEventDispatcher;

    public function removeListenerWhenFired(callback:Function, useCapture:Boolean = false):Function
    {
        return function (event:Event):void
        {
            var eventDispatcher:IEventDispatcher = IEventDispatcher(event.target)
            eventDispatcher.removeEventListener(event.type, arguments.callee, useCapture)
            callback(event)
        }
    }
}

然后，您可以收听如下事件：

Then you can listen for events like so:

import your.package.removeListenerWhenFired

// ... class definition

    sprite.addEventListener(MouseEvent.CLICKED, 
        removeListenerWhenFired(
            function (event:MouseEvent):void {
                ... do something
            }
        )
    )

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